Small engine with points?

[rgr33]

Your experience is similar to what I went through with a free to me Troybilt tiller Hard to start, and sickly when running. Fussed with it for 3 summers.

Over the winter, I noticed Harbor Freight had a good sale price on the Predator motors.
I bought one, super easy to install, and curse myself for all the crap I went through with the original motor.
Much happier now

 

[2manyrocks]

Other than having to replace belts, the tillers themselves are usually trouble free. They used control rods instead of cables to engage the drive. The tines were made of quality metal. Never imaged I would see the day when these old kohlers and briggs would be replaced with chondas.

 

[dfkrug]

...the valves are not sealing and you are loosing compression.

This is one of the reasons I have never been a fan of the old flatheads. To get some clearance for the valves to seal, the OP will have to grind a bit off the ends of the valves.

I much prefer the OHV engines, where valve clearance is super easy to check and adjust. But these adjustments are needed way more often.

Now, back to my 2002 vintage flathead Tecumseh project...

 

[CalG]

I have to ask, how does an engine that starts and runs on "direct injection" of gasoline have a valve problem?

I find it VERY difficult to blame the valve lash for an engine that starts.

If it ran for long enough time to heat the valves, lengthening the stems, that would be different.

 

[dodge man]

In the port behind where the pcv valve is you can see where the valve and a lifter meet at the valve spring. I was able to fit a feeler gauge in between. I don’t think the valves are being held open but it is possible they aren’t sealing.

Another thing I’ll add. It was making oil. There was an air leak between the tank and carb and I think this was making it run rich for the brief seconds it would run. The plug would always look wet. With the air leak fixed it seems like the plug is dry now. I just don’t think it’s getting fuel.

 

[2manyrocks]

With it running when you pour fuel into the carb, it looks like a fuel delivery problem. Could be some residual rust blockage or the ethanol has caused something to loose its ability to seal so the diaphram cant quite deliver enough pressure to lift gas out of the tank.

 

[RandyT]

I have to ask, how does an engine that starts and runs on "direct injection" of gasoline have a valve problem?

I find it VERY difficult to blame the valve lash for an engine that starts.

If it ran for long enough time to heat the valves, lengthening the stems, that would be different.

Sometimes it isn't a valve lash issue. Sometimes the valve face wears to the point the surfaced don't make contact. Just worked on a Briggs 90102 a couple of weeks ago that had .005 IN and .007 Ex without touching the valves. Engine had 0 compression with a 80% bypass with leakdown tester. Found that both valves could be turned by the finger test.. After removing the carb/tank assembly could shine a light into the intake and see light around the intake valve.

That job required the use of my Neway valve face cutter and also the Neway valve seat cutter sets. And still had to hand lap the valves with grinding compound to get them to seat properly.

Symptoms of this engine was it would start on the first pull with choke but wouldn't rev up or continue to run even with full choke, but would pop off immediately on restart and do the same thing. The added fuel would create enough seal to ignite the fuel, but couldn't continue to build compression to continue to run.

 

[dodge man]

We had a decent lawnmower place that worked on small engines also. My friend that owns this tiller called him and also talked about a valve problem with it. At this point nothing would surprise me. I never actually kept it running by slowly pouring fuel in the carb, just got it started that way and then it died. I did keep it running on starting fluid though. It’s pretty volatile though so it would probably run on it even with a valve problem.

 

[dodge man]

Since the intake valve is open put your thumb on top of the exhaust valve and see if it turns. And then turn the engine over to close the exhaust valve and then try to turn the intake valve. I will bet one or both will turn with just thumb or finger pressure, which means the valves are not sealing and you are loosing compression. Have worked on 3 in the past 2 weeks with this issue.

No longer than it takes I pulled the head. Neither valve will spin when fully closed. I liked that idea but I don’t think that’s it.

I should also add that there is a small chamber under the short intake tube under the carb. That chamber is filling with gas on its own.

 

[RandyT]

No longer than it takes I pulled the head. Neither valve will spin when fully closed. I liked that idea but I don’t think that’s it.

I should also add that there is a small chamber under the short intake tube under the carb. That chamber is filling with gas on its own.

The valves appear to be sealing enough to not cause major issues. And that small well is supposed to fill with fuel. Basically the fuel pump diaphragm pumps the fuel from the tank into that well, and then vacuum created in the carb venturi caused fuel to flow up the short tube into the carb intake. Basically atmospheric pressure will only lift fuel something like 1-3/4 inch. Since the vacuum created can't lift fuel from the lower level of the tank.